The Opera Browser has always been a small player in the browser market share. This probably limits its ability to license H264 and similar proprietary formats leaving HTML5 video unplayable. This is how to fix it.
First thing for a software engineer to do once he/she does a fresh Ubuntu installation is to install Git the distributed version control system used for managing code in software development.
If you are still copying content using the mouse, its high time you learn about xclip, the cool Linux tool that lets you copy paste using the traditional clipboard or using the mouse middle button.